Pull tab for cam lock sliders

ABSTRACT

A cam lock slider for slide fasteners and a method of making the same are disclosed, wherein there is provided a pull tab having cam means for locking the slider against movement on a slide fastener. The cam means comprises a pair of identical tongues bifurcated at one end of the body of the pull tab and each curled around a reinforcing core into the form of a roll, said reinforcing core being integrally formed with each tongue and held in intimate contact with the inner peripheral surface of the tongue when the latter is curled.

States Patent [191 ilnite Watanabe [451 Dec. 10, 1974 PULL TAB FOR C AMLOCK SLIDERS [75] Inventor: Hlrokazu Watanabe, Kurobe, Japan [73]Assignee: Yoshida Kogyo Kabushlki Kaisha,

Tokyo, Japan [22] Filed: Dec. 12, 1973 [21] Appl. No.: 426,666

[30] Foreign Application Priority Data Dec. 14, 1972 Japan 47-125428[52] US. Cl. ..-24/205.14 A, 29/409 [51] Int. Cl A44b 19/30 [58] Fieldof Search 24/205.14 A, 205.14 K; 29/409 [5 6] References Cited UNITEDSTATES PATENTS 2,865,075 12/1958 Firing ..24/205.l4A

2,978,773 4/1961 Erdmann 24/205.l4 A

Primary Examiner-Bernard A. Gelak Attorney, Agent, or Firm-Hill, Gross,Simpson, Van Santen, Steadman, Chiara & Simpson [5 7] ABSTRACT A camlock slider for slide fasteners and a method of making the same aredisclosed, wherein there is provided a pull tab having cam means forlocking the slider against movement on a slide fastener. The cam meanscomprises a pair of identical tongues bifurcated at one end of the bodyof the pull tab and each curled around a reinforcing core into the formof a roll, said reinforcing core being integrally formed with eachtongue and held in intimate contact with the inner peripheral surface ofthe tongue when the latter is curled.

1 Claim, 10 Drawing Figures PATENTEDDEE 1 01914 3.852.852

sum 2 or 2 FIG.4Q FlG. 4b FIG.

FIG. 4d

FlG.4d-

BACKGROUND OF THE INVENTION This invention relates to improvementsin'cam lock sliders for slide fasteners, more particularly to theconstruction of a slider pull tab, and to a method of making the same.

Generally, the pull tabs assembled on cam lock sliders are formed bydie-casting or pressing a blank metal. While the die-casting process canadvantageously produce locking cams of any adjusted shape and size, ithas the drawback that restrictions are imposed upon the type of metalsthatcan be die-cast and hence, the cam lock portions of a die-cast pulltab are relatively weak and susceptible to wear in repeated use. Forthis reason, most die-cast pull tabs are considered not suitable forsliders provided on mens trousers, labor uniforms and other garments orarticles such that are handled roughly and are subjected to greatconcentration of force;

On the other hand, press-formed pull tabs may be provided with lockingcams of sufficient strength to withstand severe stresses and are mostlyused on sliders attached to the above exemplified articles. A typicalprior-art construction of such press-formed pull tab includes a cam orcams formed into a roll. by bending over or curling a tongue at one endof the pull tab body. Such roll cam has resultant internal space and istherefore liable to become crushed or otherwise deformed when thegarment is laundered or pressed.

A more recent cam lock slider is known wherein the pull tab is providedwith a pair of identical cams formed from bifurcated tongues which areswaged inwardly from opposite sides so that a portion of the stock ofeach tongue is drifted downward to close up the space between the camsand the adjacent surface of the pull tab body. Such cams being solid maybe exempt from becoming crushed as was encountered with the roll type ofcam having an internal space. However, as a result of lateral swaging ofthe side wall of the tongue, the peripheral wall of the cam is thinnedout or reduced for the amount of the stock being drifted to close up'theaforesaid space. Therefore, such cam is not wholly satisfactory asregards mechanical strength. Another difficulty arising from such swagedcam is that the outer surface of its peripheral wall tends to inclineinwardly relative to the plane of the pull tab so that when the pull tabis swung into locked position, the outer marginal edge of the cam wallalone abuts against the fastener elements and is therefore prone tobecome locally worn upon repeated locking operation of the slider. Inaddition, the method employed for the manufacture of such cams has thedrawback that desired accuracy as regards the form and dimensions of thecam is difficult to achieve.

SUMMARY OF THE INVENTION Whereas, it is an object of the presentinvention to provide an improved cam lock slider of this character whichwill eliminate the above noted difficulties of the prior art sliders andwhich more specifically includes substantially solidly formed camshaving sufficient thickness throughout their length to withstand greaterpressure and desired accuracy as regards the form and dimensions suchthat their camming surfaces are disposed in uniformly effective lockingengagement with the fastener elements.

This and other objects and features of the invention will be betterunderstood from the following description taken in conjunction with theaccompanying drawings which illustrates by way of example only apreferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a pulltab provided in accordance with the invention;

FIG. 2 is a transverse sectional view taken along the line II-II of FIG.1;

FIG. 3 is a longitudinal sectional view through a slider body of theconventional form on which the pull tab is assembled and shown in lockedposition; and

FIGS. 4a through 4g, inclusive, are explanatory views utilized to showdifferent stages of forming the locking cams integrally with the pulltab.

DESCRIPTION OF THE PREFERRED I EMBODIMENT Referring now to the drawingsin which like numerals refer to like parts throughout the several views,and firstly to FIG. 3, the numeral 10 refers generally to a sliderhaving upper and lower spaced wing members 11 and, 12 connected togetherat one end by an integral neck 13. The upper wing 11 is provided with abail 14 to which a pull tab 15 is pivotally connected. The pull tab 15is provided with a pair of identical, laterally spaced locking cam rolls19, 20 which are adapted to extend through respective slots 11a in theupper wing 11 when the pull tab is swung to locking position and pressthe fastener elements E against an internal recess 16 in the lower wing12, thereby locking the slider against movement on a slide fastener (notshown v The pull tab 15 which forms the subject matter of the presentinvention is shown in finished form in FIG. 1, and it comprises arectangular body 17 provided at one end with an opening 18 forconvenience in operating the pull tab and at the opposite end with apair of locking cam rolls 19, 20 formed by bifurcated tongues 21,22extending on opposite sides of a slot 23 and bent over or curledbackward each about a reinforcing core 24, and opposed trunnions 25,26extending inwardly from the inner edges of thetongues 21,22 into theslot 23 and adapted to connect the pull tab pivotally to the slider 10.

Referring to FIGS. 4a through 4g, there are shown different stages inthe manufacture of the pull tab 15 according to the invention. In thefirst stage shown in FIG. 4a, a starting metal blank 15a is stamped outwhere indicated in hatched lines to form a square opening 18a at one endfor convenience in manipulating the tab and to reveal scrap portion 27contiguous to tongue-forming portions 21a,22a at the opposite end. Thechain-dotted lines indicate the contour along which the blank 15a iseventually cut or stamped out into a final form.

In the second stage of. the operation, the scrap portions 27 are swagedfrom the position of FIG. 4b to the position of FIG. 4b" whereupon partof the stock of the scrap portions is drifted sidewise to provide aflattened ear portion 24a which will be reformed subsequently into thereinforcing core 24. The scrap portions 27 are then cut away as shown inFIG. 40, leaving the flattened ears 24a with the tongue-forming portions21a,22a.

This cutting operation constitutes the third stage in which each ear 24ais provided with a rounded peripheral contour as shown, along which thetongue-forming portion 21a, (22a) is folded into a roll form as laterdescribed. In the fourth stage of the operation which is illustrated inFIG. 4d, the ear portions 24a are bent upright to projectperpendicularly beyond the upper surface of the blank 15a, as this isseen from a change in the position from FIG. 4d to FIG. 4d'

In the fifth stage illustrated in FIG. 4e, the blank 15a is stamped outwhere indicated in hatched lines to provide a polygonal opening or slot23a, on opposite sides of which slot are formed bifurcatedtongue-forming portions 2la,22a. The slot 23a is configured such thatthere are produced inwardly extending opposed trunnions 25,26.

The bifurcated tongues 21,22 are bent over or curled progressivelybackward as depicted in FIG. 4f and better in FIG. 4f, which constitutesthe sixth stage wherein the ear portion 24a serves as a winding core 24about which each tongue is bent. During this bending operation, the earportion 24a is rotated in position and is brought into intimate contactwith the inner peripheral surface 28 of each tongue adjacent thetrunnion 25,(26) thereby filling the space which would otherwise beformed in the curled tongue. The ear portion 24a now thus functions asthe reinforcing core 24 adapted to prevent the tongue 2l,(22) from beingcrushed.

The blank 15a is finally processed to remove by cutting the longitudinalmarginal scrap portions 30 as shown in FIG. 4g. The pull tab 15resulting from this final stage may be further processed to spread apartthe bifurcated tongues 21,22 to the position shown in FIGv 1, ifnecessary, to facilitate the assembling of the pull tab to the bail 14of the slider 10.

Advantageously, the locking cam rolls 19,20 formed bythe bifurcatedtongues 21,22, respectively, after the various stages of thepress-forming operation can retain sufficient strength against severeexternal pressure because the thickness (t') of the tongue 2l,(22) asmeasured diametrically of the cam roll remains equal to the thickness(t) of the blank 15a, as shown in FIG. 2. Also advantageously,,thetongue 2l,(22) is bent over with its outer peripheral surface or cammingsurface 29 lying in a plane parallel with the plane of the upper surfaceof the pull tab body 17, so that the cam roll 19,( 20) can abutuniformly through its entire camming surface against the fastenerelements E to effect reliable locking of the slider upon the fastenerelements.

Having thus described the invention, it will be understood that theinvention is not to be limited to the precise form and constructionherein advanced, but various changes or modifications may be madetherein without departing ,from the scope of the appended claims.

What is claimed is:

l. A pull tab for slide fastener sliders which cornprisesa tab bodyhaving a slot adjacent one end, bifurcated tongues integral with saidbody and extending on opposite sides of said slot, an inwardly directedtrunnion extending from each of said bifurcated tongues into said slotand adapted to connect the pull tab pivotally to a slider, and'areinforcing core integral with and projecting perpendicularly from aportion of said tongue, said tongue, including said portion, being bentover backward around said core substantiallyinto the form of a rollserving as a locking cam, said tongue having a thickness as measureddiametrically of the roll substantially equal to thatof said tab body,and said reinforcing core being held in intimate contact with the innerperipheral surfaces of said tongue.

1. A pull tab for slide fastener sliders which comprises a tab bodyhaving a slot adjacent one end, bifurcated tongues integral with saidbody and extending on opposite sides of said slot, an inwardly directedtrunnion extending from each of said bifurcated tongues into said slotand adapted to connect the pull tab pivotally to a slider, and areinforcing core integral with and projecting perpendicularly from aportion of said tongue, said tongue, including said portion, being bentover backward around said core substantially into the form of a rollserving as a locking cam, said tongue having a thickness as measureddiametrically of the roll substantially equal to that of said tab body,and said reinforcing core being held in intimate contact with the innerperipheral surfaces of said tongue.